The advent of Light Emitting Diode (LED) technology and it's progressive development has exposed the shortcomings of Xenon Bulbs in areas of short battery life. The increasing use of battery operated tools in workplaces and the need for energy efficient bright light and increased durability led to the design of LEDs in flashlights powered from batteries.
Currently, tools and flashlights are designed to use just one battery voltage. Although two close voltages have been used (9.6 and 12.0), performance (brightness or speed) are still proportional to input voltage. Thus, it may be advantageous to have a flashlight that worked with any battery input voltage, while maintaining even brightness throughout its use. This capability offers the user great flexibility in leveraging any of his existing batteries. LED technology also demands that the LED be driven at regulated junction temperature conditions giving a user years of lifetime and eliminating the need for replacement of Xenon bulbs.
Targeted application scenarios in automotive repair or MRO (Maintenance and Repair Organizations) require bright light in the range of 120-170 lumens. This may be achieved with a series of LEDs driven at 0.35 A by a power source. LED's with forward voltage in range of 3.2-3.8V when connected in series represent a total voltage drop of 9V and greater. (i.e. 3 or more LEDs in series, each producing ≈60 lumens). Highly cost effective and efficient Buck operation cannot be incorporated as the output voltage will be more than certain battery voltage ranges. Also, optically converging the beams from three different LED's towards a single beam output may be a challenge.